Health and Science

Yale researcher says new coronavirus saliva test 'might miss' people with low infection levels

Key Points
  • Yale researcher Anne Wyllie told CNBC on Tuesday the school's new saliva-based test for the coronavirus may not always detect people who have low infection levels.
  • "There's more of a chance that we might miss that very, very low viral load, so when the virus is only starting to pick up in an individual,"  Wyllie said on "Squawk Box." 
  • But that potential weakness can be offset by regular testing, Wyllie emphasized.
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Yale researcher on Covid-19 saliva test that was granted FDA approval

Yale University researcher Anne Wyllie told CNBC on Tuesday that the school's new saliva-based test for the coronavirus may not always detect people who have really low infection levels. 

"There's more of a chance that we might miss that very, very low viral load, so when the virus is only starting to pick up in an individual,"  Wyllie said on "Squawk Box." 

But that potential weakness can be offset by regular testing, Wyllie emphasized.

"We're wanting that frequent testing. So if you're being tested twice a week — even better if you can be tested more — you might get missed one day if you've got very, very low amounts of the virus in you. But if that viral load starts to increase, because you're having frequent testing, we'll quickly pick that up the next time," she said. 

Yale describes its test, which received emergency approval Saturday from the Food and Drug Administration, as "simpler, less expensive, and less invasive" than common nasal swab tests. In a press release, Yale said it hoped to make testing more widely available by keeping costs low and developing a test that can be processed more quickly. 

Yale's test was developed in conjunction with the NBA and its players union, which provided more than $500,000 in funding, according to ESPN. The test was used on NBA players and staff in the run-up to the league's restart in Florida. 

Results of Yale's study of its test have not yet been peer reviewed

Wyllie, an associate research scientist in epidemiology, said Yale's test has ability to detect the coronavirus that is "quite on par with many of the other traditional [polymerase chain reaction] tests that are already out there."

PCR tests, which detect a virus' genetic material, are seen to be the most accurate type on the market. The Yale test relies on PCR but simplifies the process.

The sensitivity of Yale's test decreases slightly in patients who have lower levels of the virus, Wyllie said. "It's about 90% sensitive in patients. About 88% to 90% in asymptomatic, healthy individuals," she added.

Sensitivity is the rate at which a test will correctly identify someone who has the virus. 

The U.S. response to the coronavirus pandemic has been hampered by testing challenges, including supply chain shortages and delays in turnaround time for results. Tests that are more widely available and can give results quickly yet accurately are seen as important as communities try to reopen workplaces and schools. 

Wyllie noted that Yale's test is not one of the so-called rapid tests that can produce results in 10 to 15 minutes, for example. Saliva samples still must go to a lab. But because of the way the test was designed, she said labs should be able to run more samples than other variations. 

"We do hope that we can see, maybe in some situations, same-day results. If not, what we're really striving for is to get below that 24-hour time frame that we're just not seeing in many places at the moment," she said. 

Yale hopes its test can be introduced at laboratories around the U.S. more broadly within a couple months, Wyllie said. Labs must contact Yale so the university can "make sure that it's set up properly, to make sure they've got the equipment that's available." 

"So I'm hoping that we'll see, at least within the next month, more and more labs starting to roll this out, starting to make it available," she said. "Clearly, we really do just need more testing at the moment."

Dr. Scott Gottlieb told CNBC on Monday he believes Yale University's saliva-based coronavirus test is an important development in the United States' pandemic response. "It's easy to use. It's unlikely to be in limited because of shortages in the testing supply chain," the former FDA chief added. "It's something that we can roll out on a very wide fashion."

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Former FDA chief Scott Gottlieb on significance of approval of Covid saliva test